1. Field of the Invention
The present invention relates to a power breaker having at least one arching chamber filled with an insulating medium.
2. Discussion of Background
Patent Specification EP 0 3 13 813 B1 discloses a power breaker whose arcing chamber has erosion contacts, the two of which are moved in opposite directions, to be precise by a drive, which is not illustrated, in conjunction with two toothed racks, which are arranged diametrically opposite one another, and in conjunction with corresponding gear wheels.
Laid-Open Specification DE 42 11 158 A1 discloses a power breaker which has an arcing chamber with two erosion contacts, one of which is designed to be moving. The arcing chamber is filled with an insulating gas, preferably pressurized SF.sub.6 gas. Arranged concentrically around the erosion contacts is a rated current path, which carries the current when the arcing chamber is in the connected state. Provided in the interior of the moving erosion contact is a heating area to which hot gas at an increased pressure is applied from the arcing zone of the arcing chamber. The heating area is connected by means of a narrow heating channel to the arcing zone. This heating channel is designed to be comparatively long and has a right-angle bend. This bend impedes the hot gas produced by the arc flowing into the heating area, since it reflects pressure waves. These pressure waves partially block the flow in the direction of the heating area. When the process of blowing out the arc starts, this bend thus also impedes the flow into the arcing zone, therefore somewhat reducing the cooling effect of the blowing process. During disconnection, the heating area is additionally fed with cold gas from a compression area, in a known manner.
Patent Specification EP 0 163 943 B1 discloses a concentrically constructed power breaker which has one power current path which is concentrically surrounded by an axially extending heating area. The power current path has a moving erosion contact and a stationary erosion contact. Located between the erosion contacts and the heating area there is an intermediate area. After contact disconnection, the insulating gas is first of all heated up in the intermediate area by the arc which is then produced. This intermediate area enlarges the arcing zone in this power breaker. The arcing zone in this power breaker is connected by means of an annular gap, which extends radially outwards, to the heating area, which is arranged symmetrically with respect to the annular gap and into which the hot gas produced in the arcing zone flows. The hot gas is temporarily stored in this heating area. The heating area is rigidly connected to the stationary erosion contact. In this embodiment of the power breaker, the cold insulating gas in the heating area is not mixed particularly effectively with the hot gas flowing in during the disconnection process. In addition, the pressure rise in the heating area takes place with a certain time delay, since time is required in advance to heat up the insulating gas in the intermediate area.
Laid-Open Specification DE 42 00 896 A1 discloses a power breaker which has an arcing chamber with an external rated current path and two stationary erosion contacts which are at a distance from one another. The arcing chamber is filled with an insulating gas, preferably pressurized SF.sub.6 gas. When the arcing chamber is in the connected state, the two erosion contacts are electrically conductively connected to one another by means of a moving bridging contact. The bridging contact concentrically surrounds the cylindrically designed erosion contacts. The bridging contact and the two erosion contacts form a power current path, which carries current only during the disconnection process. During a disconnection process, the bridging contact slides down from a first of the erosion contacts and strikes an arc which initially burns between the first erosion contact and the end of the bridging contact facing it. As soon as this end reaches the second erosion contact, the base of the arc commutates from the end of the bridging contact onto the second erosion contact, and the arc now burns between the two erosion contacts. The gas which is heated in the arcing zone flows through a long heating channel into a heating area which is arranged in the interior of the bridging contact and where it is temporarily stored. The heating area is additionally fed, in a known manner, with cold gas from a compression area during the disconnection process. The pressurized insulating gas which is required to blow out the arc is then introduced into the arcing zone through the heating channel. The comparatively long heating channel causes considerable flow resistance, and the energy lost because of flow losses is then not available for blowing out the arc.